This Appendix provides some background information about using Wireless LANs (WLANs).
Wireless LANs can work in either of two (2) modes:
Ad-hoc Mode
Infrastructure Mode
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Access Points can only function in "Infrastructure" mode, and can communicate only with Wireless Stations which are set to "Infrastructure" mode. |
BSS
A group of Wireless Stations and a single Access Point, all using the same ID (SSID), form a Basic Service Set (BSS).
Using the same SSID is essential. Devices with different SSIDs are unable to communicate with each other.
ESS
A group of Wireless Stations, and multiple Access Points, all using the same ID (ESSID), form an Extended Service Set (ESS).
Different Access Points within an ESS can use different Channels. In fact, to reduce interference, it is recommended that adjacent Access Points SHOULD use different channels.
As Wireless Stations are physically moved through the area covered by an ESS, they will automatically change to the Access Point which has the least interference or best performance. This capability is called Roaming. (Access Points do not have or require Roaming capabilities.)
The Wireless Channel sets the radio frequency used for communication.
WEP (Wired Equivalent Privacy) is a standard for encrypting data before it is transmitted.
This is desirable because it is impossible to prevent snoopers from receiving any data which is transmitted by your Wireless Stations. But if the data is encrypted, then it is meaningless unless the receiver can decrypt it.
If WEP is used, the Wireless Stations and the Access Point must have the same settings for each of the following:
WEP
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Off, 64 Bit, 128 Bit
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Key
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For 64 Bit encryption, the Key Table must match.
For 128 Bit encryption, the Key value must match. |
WEP Authentication
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Open System or Shared Key.
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To allow Wireless Stations to use the Access Point, the Wireless Stations and the Access Point must use the same settings, as follows:
Mode
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On client Wireless Stations, the mode must be set to
"Infrastructure".
(The Access Point is always in "Infrastructure" mode.) |
SSID (ESSID)
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Wireless Stations must use the same SSID (ESSID) as the Access Point they
wish to connect to.
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WEP
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The Wireless Stations and the Access Point must use the same settings for
WEP (Off, 64 Bit, or 128 Bit).
WEP Key: If WEP is enabled, the Key Table (for 64 Bit encryption)
or Key (for 128 Bit Encryption) must be the same on the Wireless Stations and
the Access Point.
WEP Authentication: If WEP is enabled, all Wireless Stations must
use the same setting as the Access Point (either "Open System" or "Shared
Key").
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